Finding the Fourth Proportional to 1,919.39, 2,879.69 and 686.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,919.39 : 2,879.69 = 686.78 : x
2. Step 2: Convert to fraction form
   1,919.39/2,879.69 = 686.78/x
3. Step 3: Cross multiply
   1,919.39x = 2,879.69 × 686.78
4. Step 4: Simplify right side
   1,919.39x = 1,977,695.67
5. Step 5: Solve for x
   x = 1,977,695.67/1,919.39
6. Step 6: Final answer
   x = 1,030.38